This invention relates to an improved damper assembly construction for high temperature or corrosive gases and particularly relates to an improved damper assembly with means therein for permitting expansion and contraction of the damper blade over a wide temperature range.
During the operation of blast furnaces, cupolas, and other types of furnaces used in the metal producing industry, hot gases emanate from the mouth of the furnaces and are usually caught in fume hoods or the like wherein blowers in flow communication with the fume hood remove the fumes emanating from the furnaces thereby preventing pollution of the air in the metal making area. These fumes contain a large percentage of particulate material and are received in the fume removal system at temperatures of as high as and sometimes in excess of 2000.degree. F. In these fume removal systems, damper assemblies are utilized for regulating the flow through the system and these damper assemblies are subjected to a wide range of temperatures. In the prior art, these assemblies are generally cooled by water or other means in order to prevent warping, cracking and excessive oxidation with failure of operation resulting due to the high temperature which such damper assemblies are required to withstand. Other means which have been utilized to protect the damper blade over a wide temperature range include blades made up of a plurality of metallic sections arranged to permit freedom of expansion and contraction of each of the sections in every direction, all of the parts so co-related and joined as to form a substantially gas tight barrier. However, in the case of the water cooled damper assemblies and in the metallic assemblies having means for expansion and contraction, cost of the dampers are quite expensive and weight becomes a problem. And, particularly in the case of the metallic dampers, very specific and high cost heavy materials of construction are required.